Polishing pad having insulation layer and method for making the same

ABSTRACT

The present invention relates to a polishing pad having an insulation layer and a method for making the same. The polishing pad includes a bottom layer, an insulation layer, and an abrasive layer. The bottom layer includes a fabric layer wrapped in a high polymer. The insulation layer is disposed on the bottom layer. The abrasive layer is disposed on the insulation layer. The abrasive layer is a high polymeric elastomer and has a plurality of columnar-like cells. The insulation layer can prevent the slurry from infiltrating into the bottom layer during the polishing processs to improve the polishing effect and quality.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing pad and a method for making the same, and particularly, to a polishing pad having an insulation layer and a method for making the same.

2. Description of the Related Art

Polishing generally refers to abrading a rough surface in a chemical mechanical polishing (CMP) process, in which a slurry containing abrasive grains is uniformly dispersed on a surface of a polishing pad, and meanwhile a workpiece to be polished is pressed against the polishing pad and then rubbed repeatedly and regularly. The workpiece to be polished is an object such as a semiconductor, a storage medium substrate, an integrated circuit (IC), an LCD flat glass, an optical glass, or a photoelectric panel.

In the prior art, a polishing pad is mostly fabricated by multi-layer adhesion. For example, an abrasive layer is adhered to a bottom layer with a glue (referring to a multi-layer polishing pad disclosed in Taiwan Patent Publication No. M269996); or an abrasive layer formed by a plurality of thin layers adhered together is further adhered to a bottom layer with a glue (referring to a multi-layer polishing pad for CMP disclosed in Taiwan Patent Publication No. 200513348).

After the above-mentioned polishing pads in the prior art are immersed in the slurry, a stress may easily occur as the abrasive layer and the bottom layer that are made of different materials and the glue used for adhesion have different compression ratios. In addition, the glue's adhesive strength may be gradually degraded if immersed in the slurry for a long time, resulting in poor flatness of the surface of the polishing pad. Moreover, during the polishing process, when a polishing machine applies a force to an object to be polished, a protruding portion of the surface of the polishing pad may severely abrade or scratch the surface of the object to be polished.

FIG. 1 shows a schematic view of a polishing pad in the prior art. The polishing pad 1 includes a bottom layer 10 and an abrasive layer 30. The bottom layer 10 includes a non-woven fabric 12 wrapped in a polyurethanes (PU) resin 11. The abrasive layer 30, coated on the bottom layer 10, is made of a PU resin 31, and has a plurality of drop-shaped cells 32. Though no glue or adhesive is used, the polishing pad 1 in the prior art has the following disadvantages. As the drop-shaped cell 32 has the profile of a short water drop, and the depth thereof does not exceed one half of the overall thickness of the abrasive layer 30, only a limited amount of the slurry and scraps generated during the abrasion can be stored therein. Therefore, the drop-shaped cells 32 are easily filled by the scraps generated in abrasion and gradually become smaller, thus reducing the polishing effect or scratching the surface of the workpiece to be polished, and also shortening the service life of the polishing pad 1. Moreover, the polishing pad 1 is poorly buffered when put under a large downward force.

Therefore, it is necessary to provide a polishing pad having an insulation layer and a method for making the same, so as to solve the above problems.

SUMMARY OF THE INVENTION

The present invention is directed to a polishing pad having an insulation layer. The polishing pad comprises a bottom layer, an insulation layer, and an abrasive layer. The bottom layer comprises a fabric layer wrapped in a high polymer. The insulation layer is disposed on the bottom layer. The abrasive layer is disposed on the insulation layer. The abrasive layer is a high polymeric elastomer and has a plurality of columnar-like cells.

The present invention is further directed to a method for making a polishing pad. The method comprises the steps of: (a) providing a bottom layer, in which the bottom layer comprises a fabric layer wrapped in a high polymer and has a surface; (b) forming an insulation layer on the surface of the bottom layer; (c) forming a high polymeric elastomer on the insulation layer; (d) curing the high polymeric elastomer to form an abrasive layer, in which the abrasive layer has a plurality of columnar-like cells; and (e) abrading a surface of the abrasive layer so that the abrasive layer has a plurality of surface openings.

In the present invention, the insulation layer prevents the slurry from infiltrating into the bottom layer during the polishing process so as to improve polishing effect and quality. In a preferred embodiment, the columnar-like cells are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer, and the depth of the columnar-like cells is greater than one half of the overall thickness of the abrasive layer. Therefore, when applied in the polishing process, the polishing pad may store a large amount of the slurry and scraps generated during abrasion, thus improving the polishing efficiency and preventing the surface of the workpiece to be polished from being scratched. Moreover, the polishing pad is more effectively buffered when put under a large downward force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a polishing pad in the prior art;

FIG. 2 is a schematic view of a polishing pad according to a preferred embodiment of the present invention; and

FIG. 3 is a flow chart of a method for making a polishing pad according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a polishing pad, which is applied in a chemical mechanical polishing (CMP) process to abrade or polish a workpiece to be polished. The workpiece to be polished comprises, but is not limited to, a semiconductor, a storage medium substrate, an integrated circuit (IC), an LCD flat glass, an optical glass, or a photoelectric panel.

FIG. 2 shows a schematic view of a polishing pad according to a preferred embodiment of the present invention. The polishing pad 4 comprises a bottom layer 50, an insulation layer 60, and an abrasive layer 70. The bottom layer 50 comprises a fabric layer 52 wrapped in a high polymer 51. In this embodiment, the fabric layer 52 is a non-woven fabric, and is made of polypropylene (PP), polyethylene terephthalate (PET), nylon, or a mixer thereof. The high polymer 51 is a continuous foam, and is made of polyurethanes (PU), PP, PET, a high-polymer resin, or a mixer thereof. In this embodiment, the fabric layer 52 is made of PET, and the high polymer 51 is made of PU.

The insulation layer 60 is disposed on the bottom layer 50. The insulation layer 60 is made of PU, PP, PET, a high-polymer resin, a thin metal layer, a metal powder, or any other material that can be used for insulation. In this embodiment, the insulation layer 60 comprises PU, dimethylformamide (DMF), and methyl ethyl ketone (MEK). The insulation layer 60 is coated (for example, roll-coated or blade-coated) on the bottom layer 50; however, it should be understood that, the insulation layer 60 may also be formed on the bottom layer 50 by roll-printing, transferring, or other manner. Therefore, the insulation layer 60 is bonded to the bottom layer 50 without using adhesive. Preferably, the bottom layer 50 has a surface 53 which is flat. A fiber portion 54 of the fabric layer 52 is exposed to the surface 53, such that the insulation layer 60 further enwraps the exposed fiber portion 54, resulting in an improved bond between the insulation layer 60 and the bottom layer 50.

The abrasive layer 70 is disposed on the insulation layer 60, and has a plurality of columnar-like cells 72. The abrasive layer 70 is a high polymeric elastomer 71, and is coated (for example, roll-coated or blade-coated) on the insulation layer 60; however, it should be understood that, the abrasive layer 70 may also be formed on the insulation layer 60 by roll-printing, transferring, or other manner. Therefore, the abrasive layer 70 is bonded to the insulation layer 60 without using adhesive. The abrasive layer 70 is made of PU, PP, PET, a high-polymer resin, or a mixer thereof. In this embodiment, the abrasive layer 70 is made of PU. The columnar-like cells 72 are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer 70. In this embodiment, the columnar-like cells 72 are columnar-shaped, and the depth of the columnar-like cells 72 is greater than one half of the overall thickness of the abrasive layer 70. The columnar-like cells 72 properly communicates with each other.

In this embodiment, the polishing pad 4 has a compression ratio of 5% to 50%, a compression-recovery ratio greater than 80%, a thickness of 0.5 to 3.0 mm, and a density of 0.2 to 0.6 g/cm3.

FIG. 3 shows a flow chart of a method for making a polishing pad according to a preferred embodiment of the present invention. Referring to FIGS. 2 and 3, and Step S31, a bottom layer 50 is provided. The bottom layer 50 comprises a fabric layer 52 wrapped in a high polymer 51 and has a surface 53. In this embodiment, the bottom layer 50 is formed by the following steps. First, a fabric layer 52 is provided. The fabric layer 52 may be an ordinary fiber non-woven fabric or a superfine fiber non-woven fabric, and is made of PP, PET, nylon, or a mixer thereof. In this embodiment, the fabric layer 52 is made of PET.

Then, the fabric layer 52 is immersed in a high-polymer solution, such that the high-polymer solution enwraps the fabric layer 52. The high-polymer solution may be a PU solution, a PP solution, a PET solution, a high-polymer resin solution, or a mixer thereof. In this embodiment, the high-polymer solution is a PU solution, containing 13% PU resin, 3% surfactant, 9% pigment, and 75% DMF. Finally, the high-polymer solution is cured to form the bottom layer 50.

Referring to Step S32, an insulation layer 60 is formed on the surface 53 of the bottom layer 50. In this embodiment, the insulation layer 60 is formed on the bottom layer 50 by coating (for example, roll-coating or blade-coating); however, it should be understood that, the insulation layer 60 may also be formed on the bottom layer 50 by roll-printing, transferring, or other manner. The insulation layer 60 is made of PU, PP, PET, a high-polymer resin, a thin metal layer, a metal powder, or other insulation material. In this embodiment, the insulation layer 60 comprises 17% PU and 83% MEK.

Preferably, a fiber portion 54 of the fabric layer 52 in Step S31 is exposed to the surface 53 so that the insulation layer 60 in Step S32 further enwraps the exposed fiber portion 54, resulting in a stronger bond between the insulation layer 60 and the bottom layer 50. It should be noted that the insulation layer 60 is bonded to the bottom layer 50 without using adhesive.

Referring to Step S33, a high polymeric elastomer 71 is formed on the insulation layer 60. In this embodiment, the high polymeric elastomer 71 is formed on the insulation layer 60 by coating (for example, roll-coating or blade-coating); however, it should be understood that, the high polymeric elastomer 71 may also be formed on the insulation layer 60 by roll-printing, transferring, or other manner. The high polymeric elastomer 71 may be a PU solution, a PP solution, a PET solution, a high-polymer resin solution, or a mixer thereof. In this embodiment, the high polymeric elastomer 71 is a PU solution, containing 15% PU resin, 3% surfactant, 15% pigment, and 67% DMF.

Referring to Step S34, the bottom layer 50, the insulation layer 60, and the high polymeric elastomer 71 are immersed in a curing solution so as to cure the high polymeric elastomer 71 to form an abrasive layer 70, and generate a plurality of columnar-like cells 72 in the abrasive layer 70. The columnar-like cells 72 properly communicate with each other. In this embodiment, the curing solution comprises DMF and water, and has a concentration of 15%.

Referring to Step S35, DMF is rinsed with hot water. Then, referring to Step S36, a drying step is carried out so as to obtain a semi-finished polishing pad having no exposed surface openings. Finally, referring to Step S37, a surface of the abrasive layer 70 is abraded such that the abrasive layer 70 has a plurality of surface openings, and scraps are removed by vacuum suction, so as to fabricate the polishing pad 4.

The polishing pad 4 fabricated according to this embodiment has a compression ratio of 28.30%, a compression-recovery ratio of 95.56%, a thickness of 1.6 mm, a density of 0.29 g/cm3, and a hardness of 36 Shore A.

In the present invention, the insulation layer 60 prevents the slurry from infiltrating into the bottom layer 50 during the polishing process, so as to improve the polishing effect and quality. Moreover, the columnar-like cells 72 are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer 70, and the depth of the columnar-like cells 72 is greater than one half of the overall thickness of the abrasive layer 70. Therefore, when applied in the polishing process, the polishing pad 4 may store a large amount of the slurry and scraps generated during the abrasion, thus improving the polishing efficiency and preventing the surface of the workpiece to be polished from being scratched. Moreover, the polishing pad 4 is more effectively buffered when put under a large downward force.

While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope defined in the appended claims. 

1. A polishing pad, comprising: a bottom layer, comprising a fabric layer wrapped in a high polymer; an insulation layer, disposed on the bottom layer; and an abrasive layer, disposed on the insulation layer, wherein the abrasive layer is a high polymeric elastomer and has a plurality of columnar-like cells.
 2. The polishing pad according to claim 1, wherein the fabric layer is a non-woven fabric.
 3. The polishing pad according to claim 1, wherein the fabric layer is made of polypropylene (PP), polyethylene terephthalate (PET), nylon, or a mixer thereof.
 4. The polishing pad according to claim 1, wherein the high polymer is made of polyurethanes (PU), PP, PET, a high-polymer resin, or a mixer thereof.
 5. The polishing pad according to claim 1, wherein the bottom layer has a surface, a fiber portion of the fabric layer is exposed to the surface, and the insulation layer further enwraps the exposed fiber portion.
 6. The polishing pad according to claim 1, wherein the insulation layer is coated on the bottom layer.
 7. The polishing pad according to claim 1, wherein the insulation layer is made of PU, PP, PET, a high-polymer resin, a thin metal layer, or a metal powder.
 8. The polishing pad according to claim 1, wherein the abrasive layer is coated on the insulation layer, and is made of PU, PP, PET, a high-polymer resin, or a mixer thereof.
 9. The polishing pad according to claim 1, wherein the columnar-like cells are distributed over a thickness that is at least one half of the overall thickness of the abrasive layer, and the depth of the columnar-like cells is greater than one half of the overall thickness of the abrasive layer.
 10. The polishing pad according to claim 1, wherein the polishing pad has a compression ratio of 5% to 50%.
 11. The polishing pad according to claim 1, wherein the polishing pad has a recovery ratio greater than 80%.
 12. The polishing pad according to claim 1, wherein the fabric layer is made of PET, the high polymer is made of PU, the insulation layer comprises PU and methyl ethyl ketone (MEK), and the abrasive layer is made of PU.
 13. A method for making a polishing pad, comprising: (a) providing a bottom layer, wherein the bottom layer comprises a fabric layer wrapped in a high polymer and has a surface; (b) forming an insulation layer on the surface of the bottom layer; (c) forming a high polymeric elastomer on the insulation layer; (d) curing the high polymeric elastomer to form an abrasive layer, wherein the abrasive layer has a plurality of columnar-like cells; and (e) abrading a surface of the abrasive layer, such that the abrasive layer has a plurality of surface openings.
 14. The method according to claim 13, wherein Step (a) comprises: (a1) providing a fabric layer; (a2) immersing the fabric layer in a high-polymer solution, such that the high-polymer solution enwraps the fabric layer; and (a3) curing the high-polymer solution to form the bottom layer.
 15. The method according to claim 13, wherein a fiber portion of the fabric layer in Step (a) is exposed to the surface of the bottom layer and the insulation layer in Step (b) further enwraps the exposed fiber portion.
 16. The method according to claim 13, wherein in Step (b), the insulation layer is formed on the bottom layer by coating, roll-printing, or transferring.
 17. The method according to claim 13, wherein in Step (c), the high polymeric elastomer is formed on the insulation layer by coating, roll-printing, or transferring.
 18. The method according to claim 13, wherein in Step (d), the bottom layer, the insulation layer, and the high polymeric elastomer are immersed in a curing solution, so as to cure the high polymeric elastomer to form an abrasive layer, and generate the columnar-like cells in the abrasive layer.
 19. The method according to claim 18, wherein the curing solution comprises dimethylformamide (DMF) and water.
 20. The method according to claim 13, wherein in Step (e), the surface of the abrasive layer is abraded, and scraps are removed by vacuum suction. 